Structural features of single crystals of LuB12 upon a transition to the cage-glass phase

Bolotina, N. B.; Верин, И. А.; Shitsevalova, N.; Филиппов, В. Б.; Sluchanko, N. E.

doi:10.1134/s106377451602005x

Cited by 11 publications

(6 citation statements)

References 10 publications

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“…Crystal structure. -In accordance with arguments presented in [13], the fcc symmetry of LuB 12 is notably distorted at low temperatures. Conventional software for the structure analysis results in calculated electron density (ED) replicating the symmetry of structure model if even the symmetry of real ED is distorted.…”

supporting

confidence: 88%

“…It has been recently concluded [12] that these dodecaborides RB 12 tend to form a cage-glass phase through the orderdisorder phase transition (at T * ∼ 60 K in LuB 12 ), that results in freezing of R ions in the random positions inside the B 24 cages. Besides, x-ray diffraction studies [13] discovered a significant tetragonal distortion of the atomic structure of LuB 12 in the vicinity of this phase transition.…”

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confidence: 90%

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Rattling mode and symmetry lowering resulting from the instability of the B12 molecule in LuB12

et al. 2018

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The dodecaboride LuB12 with cage-glass state and rattling modes has been studied to clarify the nature of the large amplitude vibrations of Lu ions. Discovered anisotropy of charge transport in conjunction with distortions of the conventional fcc symmetry of the crystal lattice may be attributed to coherent motion of Lu ions along singular direction in the lattice. Arguments are presented in favor of cooperative dynamic Jahn-Teller effect in the boron sublattice to be the reason of the rattling mode, lattice distortion and formation of the filamentary structure of the conductive channels. PACS numbers: 61.66.Fn, 72.15.Gd:

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supporting

confidence: 88%

mentioning

confidence: 90%

Rattling mode and symmetry lowering resulting from the instability of the B12 molecule in LuB12

et al. 2018

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“…The sample #1 was also used for the data collection at 50 K on a Huber 5042 diffractometer equipped with a pointed detector and a helium closed-cycle cryostat Displex DE-202. Although we studied before the structure of LuB 12 at 50 K [19], methods of the sample preparation and data collection on the Huber diffractometer were enriched with new details, so the new crystal #1 was measured using advanced techniques [15,20,21].…”

Section: Data Collection Data Reduction and Structure Refinementmentioning

confidence: 99%

The lower symmetry electron-density distribution and the charge transport anisotropy in cubic dodecaboride LuB₁₂

Bolotina

Dudka

Khrykina

et al. 2018

J. Phys.: Condens. Matter

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High-quality single crystals of LuB are grown using the induction zone melting method. The x-ray data are collected at temperatures 293, 135, 95, 50 K. The crystal structure of LuB can be refined with record low R-factor in the cubic Fm [Formula: see text] m symmetry group despite reiterated observations of the cubic symmetry distortions both in the unit-cell values and in the physical properties. A peculiar computing strategy is developed to resolve this contradiction. True symmetry of the electron-density distribution in LuB is proved to be much lower than cubic as a result, which correlates very accurately with anisotropy of transport properties of LuB.

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“…At the same time, it was observed that the cubic cF52 phase can also be stabilized under certain conditions (e.g., doped Sc 1−x M x B 12 with M = Zr, Y, Tm, and Lu). Just when the tetragonal form was believed to exist only for ScB 12 , a recent experiment 39 surprisingly revealed that LuB 12 has a cubic symmetry at room temperature but apparently distorts to a tetragonal symmetry at lower temperatures. A dislocation of the Lu atom from the center of the cage was proposed, 40 and no refined structure data have been available for this phase to date.…”

Section: ■ Introductionmentioning

confidence: 99%

Thermodynamic Ground States of Multifunctional Metal Dodecaborides

et al. 2019

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A large class of metal dodecaborides (MB12) is currently raising great expectations as multifunctional materials, but their refined structures are not fully resolved, which severely limits the understanding of structure–property relationships. Here, we report that the tetragonal tI26 structure is the thermodynamic ground state of ScB12, and we predict the tetragonal YB12, ZrB12, and HfB12 to be metastable, whereas the cubic cF52 structure is the high-temperature phase of ScB12 and represents the thermodynamic ground state of YB12, ZrB12, and HfB12. Crystal structures based on experimental synchrotron data are reported for tetragonal ScB12 and cubic YB12, and high-temperature X-ray data prove the phase transformation into cubic ScB12. In both types of crystal structures, the most prominent feature is that the boron atoms are linked into a rigid three-dimensional network of interconnected, empty B12-cuboctahedra with metal atoms in large cages in form truncated octahedra consisting of 24 boron atoms. It is the uniqueness of these configurations that causes unusual functionalities, i.e., the coexistence of high hardness, low density, and good electrical conductivity. Furthermore, we elucidate that these physical properties are of electronic origins. These findings not only resolve the longstanding structural puzzle of this family of MB12 but also provide crucial insights into the underlying nature of their remarkable properties.

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Structural features of single crystals of LuB12 upon a transition to the cage-glass phase

Cited by 11 publications

References 10 publications

Rattling mode and symmetry lowering resulting from the instability of the B12 molecule in LuB12

Rattling mode and symmetry lowering resulting from the instability of the B12 molecule in LuB12

The lower symmetry electron-density distribution and the charge transport anisotropy in cubic dodecaboride LuB₁₂

Thermodynamic Ground States of Multifunctional Metal Dodecaborides

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Structural features of single crystals of LuB12 upon a transition to the cage-glass phase

Cited by 11 publications

References 10 publications

Rattling mode and symmetry lowering resulting from the instability of the B12 molecule in LuB12

Rattling mode and symmetry lowering resulting from the instability of the B12 molecule in LuB12

The lower symmetry electron-density distribution and the charge transport anisotropy in cubic dodecaboride LuB12

Thermodynamic Ground States of Multifunctional Metal Dodecaborides

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Product

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The lower symmetry electron-density distribution and the charge transport anisotropy in cubic dodecaboride LuB₁₂